Gelcasting is a process in which a slurry of ceramic or metallic powders and organic monomers is poured into a mold and then formed into a gel. To retrieve the gel part, the mold may be formed from a material that is dissolvable or otherwise easily removable. For instance, the mold may be formed from wax, which can then be melted or dissolved away. Once the mold is removed, the gel can be dried and sintered to form a solid ceramic or metal part.
Additive fabrication, e.g., 3-dimensional (3D) printing, provides techniques for fabricating objects, typically by causing portions of a building material to solidify at specific locations. Additive fabrication techniques may include stereolithography, selective or fused deposition modeling, direct composite manufacturing, laminated object manufacturing, selective phase area deposition, multi-phase jet solidification, ballistic particle manufacturing, particle deposition, laser sintering or combinations thereof. Many additive fabrication techniques build parts by forming successive layers, which are typically cross-sections of the desired object. Typically each layer is formed such that it adheres to either a previously formed layer or a substrate upon which the object is built.
In one approach to additive fabrication, known as stereolithography, solid objects are created by successively forming thin layers of solid material by curing portions of a liquid photopolymer. Exposure to actinic radiation cures a thin layer of the liquid photopolymer, which causes it to harden and adhere to previously cured layers or to the bottom surface of the substrate.